The United Nations says violent incidents in Afghanistan have increased sharply this year.

A U.N. report says the average monthly number of violent incidents in the first eight months of this year stood at 2,108, a 39-percent increase over the same period a year earlier.

The report also said insurgents are conducting more complex suicide attacks involving multiple bombers and gunmen, and that on average, three such attacks have been carried out each month this year, a 50-percent rise from the same period in 2010.

In violence Wednesday, suspected Taliban militants killed eight Afghan policemen and wounded three others at a checkpoint near Lashkar Gah in southern Helmand Province. Authorities are investigating whether a police officer conspired in the attack.

NATO said five of its service members were killed Wednesday across the country. A New Zealand special forces soldier was killed in a gunbattle with insurgents near, Kabul, while three troops died in a bomb blast in eastern Afghanistan. The fifth service member died as a result of a non-battle related injury.

In other news, Afghan and coalition troops discovered three narcotics laboratories in Helmand, containing drugs with an estimated street value of more than $350 million. A coalition statement said the seizure is reportedly the largest ever made by combined forces in Afghanistan.

The laboratories, along with almost 7,000 liters of morphine solution, 100 kilograms of heroin, 80 kilograms of opium, 12 tons of chemical used to process narcotics and a quantity of drug processing equipment were destroyed.

Violence in Afghanistan is at its worst since the U.S.-led invasion in late 2001.

This comes as international forces begin pulling out of Afghanistan and transferring security responsibility to their Afghan counterparts. All foreign combat troops are set to leave the country by the end of 2014.